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       1                 :            : /* Function return value location for Linux/i386 ABI.
       2                 :            :    Copyright (C) 2005-2010, 2014 Red Hat, Inc.
       3                 :            :    This file is part of elfutils.
       4                 :            : 
       5                 :            :    This file is free software; you can redistribute it and/or modify
       6                 :            :    it under the terms of either
       7                 :            : 
       8                 :            :      * the GNU Lesser General Public License as published by the Free
       9                 :            :        Software Foundation; either version 3 of the License, or (at
      10                 :            :        your option) any later version
      11                 :            : 
      12                 :            :    or
      13                 :            : 
      14                 :            :      * the GNU General Public License as published by the Free
      15                 :            :        Software Foundation; either version 2 of the License, or (at
      16                 :            :        your option) any later version
      17                 :            : 
      18                 :            :    or both in parallel, as here.
      19                 :            : 
      20                 :            :    elfutils is distributed in the hope that it will be useful, but
      21                 :            :    WITHOUT ANY WARRANTY; without even the implied warranty of
      22                 :            :    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      23                 :            :    General Public License for more details.
      24                 :            : 
      25                 :            :    You should have received copies of the GNU General Public License and
      26                 :            :    the GNU Lesser General Public License along with this program.  If
      27                 :            :    not, see <http://www.gnu.org/licenses/>.  */
      28                 :            : 
      29                 :            : #ifdef HAVE_CONFIG_H
      30                 :            : # include <config.h>
      31                 :            : #endif
      32                 :            : 
      33                 :            : #include <assert.h>
      34                 :            : #include <dwarf.h>
      35                 :            : 
      36                 :            : #define BACKEND i386_
      37                 :            : #include "libebl_CPU.h"
      38                 :            : 
      39                 :            : 
      40                 :            : /* %eax, or pair %eax, %edx.  */
      41                 :            : static const Dwarf_Op loc_intreg[] =
      42                 :            :   {
      43                 :            :     { .atom = DW_OP_reg0 }, { .atom = DW_OP_piece, .number = 4 },
      44                 :            :     { .atom = DW_OP_reg2 }, { .atom = DW_OP_piece, .number = 4 },
      45                 :            :   };
      46                 :            : #define nloc_intreg     1
      47                 :            : #define nloc_intregpair 4
      48                 :            : 
      49                 :            : /* %st(0).  */
      50                 :            : static const Dwarf_Op loc_fpreg[] =
      51                 :            :   {
      52                 :            :     { .atom = DW_OP_reg11 }
      53                 :            :   };
      54                 :            : #define nloc_fpreg      1
      55                 :            : 
      56                 :            : /* The return value is a structure and is actually stored in stack space
      57                 :            :    passed in a hidden argument by the caller.  But, the compiler
      58                 :            :    helpfully returns the address of that space in %eax.  */
      59                 :            : static const Dwarf_Op loc_aggregate[] =
      60                 :            :   {
      61                 :            :     { .atom = DW_OP_breg0, .number = 0 }
      62                 :            :   };
      63                 :            : #define nloc_aggregate 1
      64                 :            : 
      65                 :            : int
      66                 :          0 : i386_return_value_location (Dwarf_Die *functypedie, const Dwarf_Op **locp)
      67                 :            : {
      68                 :            :   /* Start with the function's type, and get the DW_AT_type attribute,
      69                 :            :      which is the type of the return value.  */
      70                 :          0 :   Dwarf_Die die_mem, *typedie = &die_mem;
      71                 :          0 :   int tag = dwarf_peeled_die_type (functypedie, typedie);
      72         [ #  # ]:          0 :   if (tag <= 0)
      73                 :            :     return tag;
      74                 :            : 
      75   [ #  #  #  # ]:          0 :   switch (tag)
      76                 :            :     {
      77                 :            :     case -1:
      78                 :            :       return -1;
      79                 :            : 
      80                 :          0 :     case DW_TAG_subrange_type:
      81         [ #  # ]:          0 :       if (! dwarf_hasattr_integrate (typedie, DW_AT_byte_size))
      82                 :            :         {
      83                 :          0 :           Dwarf_Attribute attr_mem, *attr;
      84                 :          0 :           attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem);
      85                 :          0 :           typedie = dwarf_formref_die (attr, &die_mem);
      86         [ #  # ]:          0 :           tag = DWARF_TAG_OR_RETURN (typedie);
      87                 :            :         }
      88                 :          0 :       FALLTHROUGH;
      89                 :            : 
      90                 :            :     case DW_TAG_base_type:
      91                 :            :     case DW_TAG_enumeration_type:
      92                 :            :     CASE_POINTER:
      93                 :            :       {
      94                 :          0 :         Dwarf_Word size;
      95                 :          0 :         Dwarf_Attribute attr_mem;
      96         [ #  # ]:          0 :         if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_byte_size,
      97                 :            :                                                    &attr_mem), &size) != 0)
      98                 :            :           {
      99         [ #  # ]:          0 :             if (dwarf_is_pointer (tag))
     100                 :          0 :               size = 4;
     101                 :            :             else
     102                 :          0 :               return -1;
     103                 :            :           }
     104         [ #  # ]:          0 :         if (tag == DW_TAG_base_type)
     105                 :            :           {
     106                 :          0 :             Dwarf_Word encoding;
     107         [ #  # ]:          0 :             if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_encoding,
     108                 :            :                                                        &attr_mem),
     109                 :            :                                  &encoding) != 0)
     110                 :          0 :               return -1;
     111         [ #  # ]:          0 :             if (encoding == DW_ATE_float)
     112                 :            :               {
     113         [ #  # ]:          0 :                 if (size > 16)
     114                 :            :                   return -2;
     115                 :          0 :                 *locp = loc_fpreg;
     116                 :          0 :                 return nloc_fpreg;
     117                 :            :               }
     118                 :            :           }
     119                 :          0 :         *locp = loc_intreg;
     120         [ #  # ]:          0 :         if (size <= 4)
     121                 :            :           return nloc_intreg;
     122         [ #  # ]:          0 :         if (size <= 8)
     123                 :            :           return nloc_intregpair;
     124                 :            :       }
     125                 :          0 :     FALLTHROUGH;
     126                 :            : 
     127                 :            :     case DW_TAG_structure_type:
     128                 :            :     case DW_TAG_class_type:
     129                 :            :     case DW_TAG_union_type:
     130                 :            :     case DW_TAG_array_type:
     131                 :          0 :       *locp = loc_aggregate;
     132                 :          0 :       return nloc_aggregate;
     133                 :            :     }
     134                 :            : 
     135                 :            :   /* XXX We don't have a good way to return specific errors from ebl calls.
     136                 :            :      This value means we do not understand the type, but it is well-formed
     137                 :            :      DWARF and might be valid.  */
     138                 :            :   return -2;
     139                 :            : }